beginning directx 11 game programming [electronic resource]

The What, Why, and Howof DirectX Prior to DirectX, game makers were struggling with problems stemming fromhardware incompatibilities, making it almost impossible for everyone to enjoythe

R

11 Game Programming

Allen Sherrod and Wendy Jones

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I would like to thank the men and women at Cengage Learning who helped makethis book possible I would also like to thank Wendy Jones for all her hard work

on the previous editions of the book And I would like to give a special thanks toEmi Smith, who has been very patient and helpful with this whole process

Allen Sherrodis an experienced author in thefield of video game development.Allen’s past works include two editions of Ultimate Game Programming withDirectX, Ultimate 3D Game Engine Design and Architecture, Game GraphicsProgramming, and Data Structures and Algorithms for Game Developers Allenhas also contributed to Game Developer magazine, the Game ProgrammingGems 6 book, and the Gamasutra.com website Allen is the creator of www.UltimateGameProgramming.com.

Wendy Jonesis co-founder and CTO of Kitty Code LLC, a games studio working

on mobile and console platforms such as iPhone, Windows Phone 7, and theXbox 360 Wendy’s past experience includes working on PC, console, and mobilegame titles while working with Atari and Electronic Arts Wendy also teachesDirectX at Full Sail University and is department chair of the interactivedevelopment department Wendy can be reached through her website at www.fasterkittycodecode.com

Introduction xi

Chapter 1 The What, Why, and How of DirectX 1

What Is DirectX? 1

DirectX 10 versus DirectX 9 2

DirectX 11 versus DirectX 10 4

DirectX 11 versus OpenGL 4.0 5

Why Is DirectX Needed? 6

How DirectX Is Put Together 7

The Components of DirectX 11 7

Obsolete DirectX Components 10

Introducing Direct3D 11 12

Stages of Direct3D 11 12

Direct3D 11 Considerations 15

DirectX Tools 16

Sample Browser and Documentation 16

PIX 16

Caps Viewer 17

Diagnostic Tools 17

Texture Tool 18

Error Lookup 19

Control Panel 20

Cross-Platform Audio Creation Tool 20

C o n t e n t s

v

Game Definition File Editor 20

Down-Level Hardware 21

Summary 23

Chapter Questions 23

Chapter 2 Your First DirectX Program 27

Creating the Project 27

Adding Windows Code 29

The Main Entry Point 30

Windows Initialization 32

Windows Callback Procedure 42

Time for Direct3D 44

Adding the DirectX Libraries 45

Initializing Direct3D 47

Driver Types and Features Levels 47

Device and Swap Chain Creation 49

Render Target View Creation 53

The Viewport 55

Clearing and Displaying the Screen 56

Cleaning Up 58

Formats 58

The Blank D3D Window 59

Design of the Template Framework 60

The Direct3D Class 60

The Blank Window Demo Class 67

Updating the Application Loop 70

DirectX Error Handling Library 73

Error Handling Functions 73

Error Handling Macros 75

Summary 75

Chapter Questions 76

Chapter 3 2D Rendering 79

2D Game Development 80

Textures 81

Sprites 84

2D Geometry 86

What Is a Vertex? 87

Definition of a Triangle 91

Vertex Buffers 94

Input Layout 97

Drawing a 2D Triangle 105

2D Triangle Demo 108

Loading the Geometry 108

Rendering the Geometry 114

Texture Mapping 116

Texture Interfaces 118

MIP Maps 119

Texture Details 121

Texture Mapping Demo 122

Sprites 133

Z-Ordering 134

Sprite Image 135

Getting Sprites to the Screen 136

Positioning and Scaling Sprites 139

The Game Sprite Demo 140

Creating and Rendering the Game Sprite 143

Summary 153

What You Have Learned 153

Chapter Questions 153

On Your Own 154

Chapter 4 Text and Font Rendering 155

Text in Games 155

Adding Text 158

Textured Fonts 159

A Font System Explained 160

Creating a Font System Using Sprites 161

Advanced Topics 171

In-Game Text Boxes 172

In-Game Console Window 172

Game Menus 173

Heads-Up Display 174

Summary 174

Chapter Questions 174

On Your Own 176

Contents vii

Chapter 5 Input Detection and Response 177

I Need Input 177

Input Options 179

Keyboard Input 180

Win32 Keyboard Input 180

DirectInput Keyboard Input 183

DirectInput Keyboard Demo 198

Mouse Input 208

DirectInput Mouse Input 209

XInput—Game Controllers 215

Setting Up XInput 216

Controller Vibrations 217

XInput for Input 218

Controller Capabilities 218

Battery Life 219

Keystrokes 220

Headset Sound 221

XInput Demo 222

Summary 225

What You Have Learned 225

Chapter Questions 226

On Your Own 226

Chapter 6 3D Primer 227

XNA Math 228

Utilities 228

Points 229

Vectors 229

Vector Arithmetic 233

Distance Between Vectors 234

Determining the Length of a Vector 235

Normalize a Vector 236

Cross Product 237

Dot Product 237

3D Space 239

Coordinate Systems 239

Transformations 241

World Transformations 242

View Transformations 243

Projection Transformations 243

Transforming an Object 244

Matrices 246

The Identity Matrix 247

Matrix Scaling 248

Matrix Translation 249

Matrix Rotation 249

Matrix Concatenation 252

Cube Demo 253

Additional XNA Math Topics 269

Compiler Directives 269

Constants 270

Macros 272

Structures and Types 274

Additional Functions 279

Additional Math Structures and Topics 283

Game Physics and Collision Detection 283

Summary 284

What You Have Learned 284

Chapter Questions 285

Chapter 7 Shaders and Effects 287

Shaders in Direct3D 287

History of Programmable Shaders 288

Effect Files 289

Effect File Layout 290

Loading an Effect File 291

External Variables and Constant Buffers 292

Input and Output Structures 293

Technique Blocks 294

Rasterizer States 296

High Level Shading Language 298

Variable Types 298

Semantics 299

Function Declarations 299

Vertex Shaders 300

Contents ix

Pixel Shaders 301

Texture Color Inversion 301

Color Shifting 309

Multitexturing 311

Geometry Shaders 314

Geometry Shader Function Declaration 316

The Geometry Shader Explained 316

Introduction to Lighting 317

Summary 325

What You Have Learned 325

Chapter Questions 325

On Your Own 326

Chapter 8 Cameras and Models in Direct3D 327

Cameras in Direct3D 327

Look-At Camera Demo 328

Arc-Ball Camera Demo 334

Meshes and Models 342

The OBJ File Format 342

Reading Tokens from a File 344

Loading Meshes from OBJ Files 349

Advanced Topics 356

Complex Cameras 357

3D Level Files 360

Summary 363

What You Have Learned 363

Chapter Questions 363

Index 365

Many of us wish to create our own video games For some, gaming is a hobby, andfor others it is something fun to participate in casually But for the rest of us,gaming and the dream of making our own games is more like a passion Chancesare, if you’ve purchased this book, you are looking to turn your desire and passioninto something you can play and share with others.

About This Book

This book is the follow-up edition to Wendy Jones’s Beginning DirectX 10 GameProgramming book In this book, we teach you the basics of getting started withgame graphics using the latest iteration of Direct3D: Direct3D 11

The goal of this book is to teach you the various aspects of DirectX 11 The targetaudience for this text is beginning/intermediate C++ programmers with little to

no experience with DirectX Although past DirectX or OpenGL experience can beuseful, it is not required

When you reach the end of this book, you will have had enough experience withDirectX 11 that you should be able to explore making simple video games and demos.Ideally, you will work your way up to make complex games and demos until youfindyourself able to complete and release (even if for free atfirst) your own PC games

Recommended Knowledge

This book assumes you have knowledge and familiarity of the C++ programminglanguage You are also assumed to have a comfortable working knowledge ofVisual Studio 2010 and have completed at least a high-school level of mathe-

I n t r o d u c t i o n

xi

matics Since this book is centered on learning DirectX for thefirst time, knowingDirectX is, of course, not required for working through this book.

Throughout this book we use Visual Studio C++ 2010 Express, which can bedownloaded from Microsoft’s website at www.microsoft.com/express/Down-loads We are also using the June 2010 DirectX SDK, which can be downloadedfrom http://msdn.microsoft.com/en-us/directx

Although not required for this book, it is recommended to try Adobe Photoshopfor the creation of textures (www.adobe.com/products/photoshop/photo-shopextended/) and XSI Mod Tool 7.5 for the creation of 3D models and meshes(http://usa.autodesk.com)

Companion Website: Code and Bonus Content

Almost every chapter has code samples and demos that give you hands-onexercises of the topics discussed To follow along, view, execute, or manipulatethese code samples, you will need the book’s accompanying code, which can bedownloaded from:

Errata

Sometimes there are errors that are not caught before the book is released or thatcan even arise due to outside circumstances that we could not anticipate If youfind any errors or issues with the book, please be sure to submit them to thecompanion website at www.ultimategameprogramming.com/BeginningDX11.Also be sure to check the companion website to see if there are existing issues thatother readers have found that you mightfind useful to know

Companion Website Downloads

downloads Please note that you will be redirected to our Cengage Learning site

The What, Why, and How

of DirectX

Prior to DirectX, game makers were struggling with problems stemming fromhardware incompatibilities, making it almost impossible for everyone to enjoythe same games due to the sheer volume of hardware configurations that existed

As the industry faced the need for standardization, Microsoft introduced theWindows Game SDK for Windows 95, which became DirectX 1 DirectXprovided game makers with a single set of APIs that would almost guaranteecompatibility across different sets of PC hardware Since DirectX’s release, thenumber of games running under Windows has increased dramatically This isstill true almost 15 years later

In this chapter:

n Understanding what DirectX is

n Why DirectX is useful

n How data flows through the Direct3D 11 pipeline

n What’s new for Direct3D 11

What Is DirectX?

DirectX, Microsoft’s collection of application programming interfaces (APIs), isdesigned to give developers a low-level interface to the PC hardware runningWindows-based operating systems Each component provides access to different

Chapter 1

1

aspects of the hardware, including graphics, sound, GPU general purposecomputing, and input devices, all through a standard interface.

This ideology allows developers to write their games using standard APIswithout having to worry about the low-level interfacing with the different pieces

of hardware a customer might have Imagine the difficulty developers once faced

by trying to write code paths for the many different hardware configurations aplayer might have What if the player had a different input device? What about a

between DOS and Windows 95? What about audio hardware and drivers?What about different types and models of graphics hardware?

Having one standard API that hardware manufacturers must adhere to is muchmore ideal than writing code paths for every possible device on the market,especially since newer devices released after a game has shipped could possiblynot be recognized by the game, whereas using a standard solves this issue.DirectX is a collection of APIs used primarily by video game developers toaddress this need for standardization on the Windows and Xbox platforms It is

up to the hardware manufacturers to provide the driver layer for their devices

N o t e

The Xbox 360 uses a variation of DirectX 9.

DirectX 10 versus DirectX 9

In 2006, DirectX 10 presented a major leap forward in the DirectX SDK Usuallywhen discussing DirectX we are discussing Direct3D, which is the API withinDirectX that receives the most overhauls Most other APIs in DirectX are eitherdeprecated (meaning they are up for removal and it’s recommended that newsoftware not use them), are the same or have minor changes, or have beenremoved completely from the SDK

The Direct3D 10 API is very lightweight when compared to its predecessors, andthe API is much easier to use than past versions In fact, early versions ofDirectX were notoriously difficult to learn and use, but Microsoft has madechanges and improvements to the API over many years Direct3D 10 was notjust an upgrade but, in many respects, an API that started fresh And it indeedfelt like a fresh start with the launch of Windows Vista, DirectX 10-class

hardware, and a powerful API that was being hyped by one of the most

influential software giants in the world

The most apparent removal in Direct3D 10 was the fixed-function pipeline,

which is essentially a set of rendering states and algorithms built into the API

that allowed for the rendering of objects using common effects The

fixed-function pipeline was removed in favor of programmable shaders within

graphics hardware Graphics shaders, which will be discussed throughout this

book, are code written specifically to customize how the graphics hardware

processes geometry Graphics shaders were first introduced in DirectX 8, but

since then graphics hardware and the Shader Models that they run have evolved

to a point where they have become the star of the API

In Direct3D 9 we can render geometry, enable lighting by setting a few

properties and rendering states, have the API transform our geometry, and so

forth by calling a few Direct3D function calls In Direct3D 10 we can do all of

that ourselves and much more in shaders The key thing for beginners to keep in

mind if this is their first time learning graphics programming is that the

fixed-function pipeline was limited to whatever was built into the API, whereas

shaders allow us to create any effect, limited only by the frame-rate we deem

desirable in our games Want lighting? Call a Direct3D function to enable it and

set its properties (up to eight lights) Want to render surfaces with more than

one image? Just enable it If, however, you wish to perform pixel-based motion

blur and depth-of-field, you are out of luck using the fixed-function pipeline

Often if the fixed-function pipeline does not explicitly support it and you are not

using shaders, you cannot create the effect you want Although some coders

have found tricks and workarounds to getting some effects created without

shaders, it was often a very difficult and inefficient workaround I remember

these times well and do not miss them

Today, if we want to perform bump mapping, we can write a pixel shader that

takes the light direction, performs a calculation using it and the pixel-level

surface direction loaded from a special image known as a normal map, and

combine that with the shading of the final pixel’s color In the days before

shaders, or even when shaders were limited in the features they provided (such

as the dark ages of register combiners for early versions of OpenGL), this was

impossible, and doing even simple effects like normal mapping back then was

What Is DirectX? 3

only made possible through inefficient and often poor-quality tricks andapproximations Of course what is considered an easy effect to one persondepends on his experience level.

The leap from DirectX 9 to DirectX 10 was a huge one DirectX 10 went throughtwo iterations as the market’s acceptance caught up

DirectX 11 versus DirectX 10

Direct3D 11 builds upon Direct3D 10.1 to add a new set of features forrendering next-generation graphics The new additions to DirectX 11 includethe following:

n True multi threaded rendering support

n New hardware tessellation

n Shader Model 5.0 and object-oriented programming concepts for shaders

and LDR images, respectively

n Increased texture resolution sizes

widespread, but also the majority of Windows users now are spanning WindowsVista and Windows 7 DirectX has always taken the future into consideration,and with the number of years it takes next-generation games to be developed,DirectX 11 will be very important to gaming for many years to come

DirectX 11 versus OpenGL 4.0

OpenGL has long been considered a rival graphics API to Direct3D OpenGL

supports platforms outside of Windows-based operating systems, such as Mac

implementation at least), and a variety of mobile devices such as cell phones

and PDAs, along with other platforms Although the native device creation of

OpenGL can differ from one platform to another, the rest of the API is

considered platform independent, not including the long history of

hardware-specific extensions and features from competing entities within the OpenGL

camp DirectX, on the other hand, is available on the various Windows OSs and

the Xbox game consoles To be considered DirectX 10 or 11 compatible,

hardware must adhere to a strict compatibility list, whereas prior to DirectX

10 this was not always the case In the case of OpenGL this often led to

vendor-specific extensions that worked on limited hardware Incompatibilities within

the hardware market caused rework when trying to achieve the same result on

all supported devices

The whole Direct3D versus OpenGL debate can often seem like a religious one,

but the fact is that for many years OpenGL has lagged behind Direct3D

Microsoft has done a great job evolving Direct3D and improving it throughout

the years, but OpenGL has only lagged behind, not keeping its promises as each

new version is released, and time and time again has suffered from the same

problems of yesteryear When OpenGL 3.0 was first announced, it was thought

that OpenGL would finally move back into a position to rival Direct3D

Unfortunately, the world of OpenGL has gone through its share of ups and

downs, both within the group behind it and with how the API stacked against

Direct3D, and Direct3D has continued to dominate

OpenGL 4.0 catches up to many of the publicized features of DirectX 11, most

notably through the support of general-purpose computing using OpenCL and

tessellation, and is positioning itself to be a step closer to the promises that were

never delivered in the past, most notably with OpenGL 2.0 and OpenGL 3.0

Although OpenGL is not out of the race yet, it unfortunately needs a lot of work

to not only truly rival DirectX but also to win back the hearts and minds of

numerous Even if the API catches up, the graphics API race is a lot like high

school where the popular kid wins the election

What Is DirectX? 5

Why Is DirectX Needed?

Before the release of the Windows operating system, developers were writinggames for DOS This single-threaded, non-GUI operating system provideddevelopers with a direct path between their application code and the hardware

it was running on This had both its advantages and problems For instance,because there was a direct path between the game code and the hardware,developers could pull every ounce of power out of the machine, giving themcomplete control over how their game performed The downside included theneed to either write directly to the hardware or use a variety of third-partylibraries for any hardware they wanted their game title to support, includingeven common hardware such as video and sound cards

Video cards were especially confusing because not all video cards followed thesame standard Even though most video cards supported a series of commonresolutions, developers were forced to access video memory directly This madeeven drawing to the screen difficult Developers were definitely looking for abetter and easier way

When Windows 3.1 was released, it carried with it the same limitations thatDOS had Since Windows ran on top of DOS, it severely limited the resourcesavailable to games and took away the direct access developers had enjoyed for solong Most games written to support Windows at the time consisted mainly ofcard and board games, while most games continued to support DOS only.Microsoft released DX1 as a way of enticing developers to make games for

DOS-based systems

Microsoft’s release of Windows 95 didn’t eliminate any of these problems untilthe release of DirectX 1, also known as the Windows Games SDK It gavedevelopers a single library to write to, placing a common layer between theirgame and the PC hardware; drawing graphics to the screen had just become awhole lot easier The first version of DirectX still didn’t provide support for allthe hardware out there, but it was a great starting point in giving gamedevelopers what they had been waiting for Over the years, there have beenmultiple releases of DirectX, each one improving and adding support for newtechnologies such as network play, streaming audio, and new kinds of input

devices The latest version of DirectX includes Direct3D 11, which is compatible

with Microsoft Windows Vista and Windows 7 operating systems

How DirectX Is Put Together

DirectX is based on a collection of code libraries, each providing a common set

of functionality needed for games and multimedia applications To make sure

that your game only has to link to the necessary functionality, DirectX is

separated into multiple components

The Components of DirectX 11

The DirectX API is split into multiple components, each representing a different

aspect of the system Each API can be used independently of one another,

thereby allowing the addition of only the functionality your game requires In

the latest version of DirectX, some of the components were updated, such as

Direct3D, while others are now being maintained at their previous levels by

Microsoft until their removal (if they are deprecated) The components within

DirectX can be upgraded individually as new functionality is required

Direct2D

Direct2D is used for 2D graphics within Win32 applications It is capable of

rendering high-performance vector graphics

DirectWrite

DirectWrite is used for fonts and text rendering within a Direct2D application

DXGI

The DirectX Graphics Infrastructure, also known as DXGI, is used for the

creation of Direct3D swap chains and the enumeration of device adapters

Direct3D

Direct3D is used for all 3D graphics in DirectX It is also the API that receives

the most attention and updates Throughout this book we will largely focus on

Direct3D

How DirectX Is Put Together 7

XAudio2 is a lower-level audio processing API that is part of the XDK (XboxDevelopment Kit) and, now, the DirectX SDK XAudio2 is the replacement forDirectSound The original XAudio was used on the first Xbox video game console

XACT3

XACT3 is a higher-level audio processing API built on top of XAudio2 XACT3allows developers to use the Cross-Platform Audio Creation Tool to authorsounds in their applications Developers would use XAudio2 if they needed low-level control of their audio system or if they wanted to build their own higher-level audio system similar to XACT3 XACT3, as discussed in Appendix B,

“Audio in DirectX” from the companion website, is a powerful and incredibleeasy tool to use for game audio

XInput

XInput is the input API for the XDK and the DirectX SDK and is used forprocessing of input from all Xbox 360 controllers Essentially any controller youcan use with your Xbox 360 can be used with the PC, and XInput is the API youuse for working with these devices These devices include not only Xboxgamepad controllers but also Rock Band and Guitar Hero instrument controllers(e.g., guitars, drums, and so forth), Big Button controllers (shipped with thegame Scene It), arcade sticks (e.g., the Tekken 6 arcade stick), and so much more.XInput is the replacement for DirectInput

N o t e

XNA Game Studio is a game development tool built on top of DirectX that allows developers to

create games for both the Xbox 360 and Windows PCs using C# and NET XNA Math is the name

of the math library in the new DirectX SDK and can be used outside of the XNA Game Studio You

do not need to download the XNA Game Studio SDK.

DirectCompute

DirectCompute is a new API added to DirectX 11 that allows for

general-purpose multi threading computing using the GPU The GPU has the ability to

process many tasks in parallel, such as physics, video compression and

decom-pression, audio processing, and much more Not all tasks are suited for the GPU,

but for those that are, the possibilities are tremendous

For more information on DirectCompute, check out the book Game

Develop-ment with Microsoft’s DirectCompute for Beginners

DirectSetup

Once your game is complete, you’ll want to show it to others DirectSetup gives

you the functionality to install the latest version of DirectX on the user’s

computer It also has the ability to check the latest installed version of DirectX

Windows Games Explorer

The Games Explorer is a feature of Windows Vista and Windows 7 that allows

developers to present their games on those OSs The Games Explorer handles

things such as the game’s display, title, rating, description, region-specific box

art, content ratings (e.g., M for Mature, T for Teens, etc.), game statistics and

notifications, parental controls, and more The DirectX SDK provides plenty of

information on how to use the Games Explorer for your own games and could

be very useful when it comes time to ship a game An example of the Games

Explorer can be seen in Figure 1.1

DirectInput

DirectInput is an API for detecting input with keyboards, mice, and joysticks

Today XInput is used for all game controllers For keyboards and mice we can

use Win32 functions or we can use DirectInput, which we’ll examine later in the

book in Chapter 5 According to the DirectX SDK, DirectInput will remain in its

current form until new technologies replace it

How DirectX Is Put Together 9

Obsolete DirectX Components

The following components are either deprecated or removed from the DirectXSDK:

DirectDraw

Once used for 2D rendering, today we can use either Direct2D or Direct3D for2D graphics DirectDraw was merged with Direct3D into what was calledDirectX Graphics in DirectX 8

Figure 1.1

An example of the Games Explorer in Windows 7.

N o t e

In previous versions of DirectX, 2D drawing functionality was provided by a component called

DirectDraw Because DirectDraw is no longer being updated, you should perform all drawing using

Direct3D or Direct2D.

DirectPlay

DirectPlay was used for networking capabilities for online games It was built on

top of the UDP protocol (User Datagram Protocol) and served as a higher-level

abstraction for network communication Today the API has been removed and

is no longer part of the DirectX SDK DirectPlay was deprecated in favor of

Games for Windows Live on the PC and Xbox Live on Xbox consoles

DirectShow

DirectShow was used for multimedia rendering and recording This meant

DirectShow was able to display video files in multiple common formats, provide

DVD navigation, and much more Today DirectShow is part of the Windows

SDK and is no longer part of the DirectX SDK Alternatively, Windows Vista

and Windows 7 users can use Microsoft’s Media Foundations for media content,

which is also part of the Windows SDK This is useful for video games if they

need to display CG cut-scenes and video files

DirectMusic

DirectMusic is now a deprecated API from the DirectX 7 and earlier days for

playing audio content in applications DirectMusic offers low-level access to

audio and hardware and has been a topic in DirectX books and tutorials for

many years Today we use XAudio2 (low-level) or XACT3 (high-level) for audio

in games and media applications

DirectSound

DirectSound is another deprecated audio API used to give low-level access to

developers for their audio needs XAudio2 is its replacement We discuss audio

in detail in Appendix B,“Audio in DirectX,” located on the companion website

The Components Object Model

The DirectX API is based on the Component Object Model (COM) COM

objects consist of a collection of interfaces that expose methods that developers

How DirectX Is Put Together 11

use to access DirectX COM objects are normal DLL files that have beenregistered with the system to provide support for specific hardware in themachine For DirectX COM objects, registration happens during the installation

of DirectX While similar to Cþþ objects, COM objects require the use of aninterface to access the methods within them This is actually an advantage overstandard objects because multiple versions of an interface can be present within

a COM object, allowing for backward compatibility

For instance, each version of DirectX included a new DirectDraw interfaceaccessible through the API, while still containing the previous version so as not

to break existing code Therefore, games created using DirectX 7 are able towork with DirectX 9 In other words, older games can be installed and playedusing the latest version of the DirectX runtime

An additional advantage to COM objects is their ability to work with multiplelanguages, not just Cþþ Developers can use Visual Basic, Cþþ, or C# and stilluse the same DirectX libraries As Microsoft updates and adds new functionality

to DirectX, the version numbers of each updated component will increase You’llfind that not all the included components exist at the same version level Forinstance, DirectInput remains at version 8.0, while Direct3D is now at version 11

Introducing Direct3D 11

The release of Windows 7 has brought with it the release of Direct3D 11.Direct3D 11 is compatible with Windows Vista and Windows 7, along withDirectX 10-class hardware Certain features of DirectX 11, such as tessellationand Shader Model 5.0, require DirectX 11-class hardware But most of the APIcan be used with DirectX 10-class hardware

Stages of Direct3D 11

Direct3D is more than just an API; it’s a tool for transforming geometric shapesand images into a living, breathing world Even though you can treat manypieces of Direct3D as a black box and not have to worry about the implemen-tation details, it is a good idea to understand at least an overview of how itworks

Direct3D processes your scene in multiple stages, with each stage performing aspecific set of tasks resulting in a final image These stages are known as Direct3D’srendering pipeline, and a screenshot of each can be seen in Figure 1.2

The first stage of Direct3D’s pipeline, called the Input-Assembler (IA) stage, can

be thought of as the building-block stage In this stage we set the geometry we

are going to render along with the necessary information Direct3D needs to

perform that task

The second stage is the vertex shader (VS) stage A vertex is a single point that

makes up a shape, such as a triangle In a vertex shader we can run code that

operates on each vertex, much of which depends on the effect we are setting up

for Shaders will be discussed more throughout this entire book A vertex shader

always takes a single vertex as input and outputs a single vertex This vertex data

was supplied by the data set using the input assembler

The third, fourth, and fifth stages are optional stages that deal with tessellation

Tessellation is an advanced topic that uses two new shaders to Direct3D called

the hull and domain shaders Hardware tessellation, in a nutshell, is the process

of taking input geometry and increasing or decreasing its level of detail This

allows for very high polygonal models to be rendered in real time with polygon

counts in the hundreds of thousands or even the millions By having the

hardware create the detail of the geometry, the application only has to submit a

Figure 1.2

The stages of Direct3D 11.

Introducing Direct3D 11 13

small amount of data that defines the low-level model This model can be in theform of patches, which is a 3D modeling The hardware takes this low-levelmodel and makes it higher level Subdividing polygons means to take a polygonand divide it into smaller pieces.

The hull shader takes its input from the output of the vertex shader, which isoperating on control points and data versus traditional vertices, and producesoutput control points for what are known as patches The tessellation stage,which appears between the hull shader and domain shader stages, is a fixed-function stage that takes the output from the hull shader and subdivides the data

on hardware The domain shader is responsible for generating the vertex of asubdivided point

The sixth stage, the geometry shader (GS), is also an optional shader stage If there is

no tessellation being performed, the geometry shader stage occurs after the vertexshader stage Geometry shaders operate on entire shapes such as triangles, whereasthe vertex shader operates on a single point of a shape The geometry shader has theability to essentially create or destroy geometry as needed, which depends largely onthe effect you are trying to create One common example of geometry shaders isgenerating shadowing geometry from a model by creating what is known as ashadow volume Another example is the generation of particles used to create particleeffects such as rain or explosions by taking a list of points that act as the center of theparticles and generating polygons around them

The seventh stage, the Rasterizer, has the job of determining what pixels are visiblethrough clipping and culling geometry (we’ll discuss this in Chapter 6), setting upthe pixel shaders, and determining how the pixel shaders will be invoked

The eighth stage is the pixel shader (PS) stage In the pixel shader stage, theshader receives the geometric data from all previous stages and is used to shadethe pixels (sometimes referred to as fragments) that comprise that shape Theoutput of the pixel shader is a single color value that will be used by the finalstage to build the final image displayed to the screen If there are no tessellation

or geometry shaders, the pixel shader receives its input from the vertex shaderdirectly The input to the pixel shader is technically interpolated data—that is,data that is generated between the points (vertices) of a shape We’ll discuss thismore in the next chapter

The final stage, the output merger (OM) stage, is where it all comes together.

The OM takes all of the output pieces from the other stages of the pipeline and

builds up the final image to send to the screen

Direct3D 11 Considerations

Some of you may already be familiar with writing games using DirectX, and if

so, there are a few things you need to be aware of when converting your game to

the latest version of Direct3D If updating from Direct3D 10 to Direct3D 11, the

process is fairly straightforward, and most of the work will be to replace

Direct3D 10 calls with their Direct3D 11 equivalent Direct3D 11 is more of a

superset of Direct3D 10 and 10.1, so there is not a lot that will need to be done

Going from Direct3D 9.0 to 11.0 is another story

When coming to Direct3D 11 from Direct3D 9, the biggest change is the

removal of the fixed-function pipeline Previously you could choose one of the

default ways to process your 3D scene, and Direct3D would handle the clipping,

lighting, and the shading Today, with D3D10 and D3D11, all this functionality

needs to be specifically handled using the programmable pipeline Chapter 7 is

about shaders, and its purpose is to bring you fully up to speed with all that is

included in Direct3D 11 Throughout the entire book we’ll be using shaders and

discussing them as necessary before we reach the comprehensive discussion in

Chapter 7

Another of the more major changes is the removal of the CAPS bits In previous

versions of Direct3D, you had to check the capabilities of the underlying video

hardware to make sure that certain functionality like pixel shaders was available

to use Now, any features not provided by the hardware are emulated by the

system in software, ensuring you always have the full range of functionality to

play with This will greatly simplify the initialization code for games using

D3D10 It is also much needed, since in the past some hardware vendors

supported only a subset of features, which caused issues when dealing with

supporting different pieces of hardware To be considered DirectX 10- or

11-compatible today, hardware must strictly follow guidelines for compliance

Direct3D 9.0 is close to having a completely different API It is not possible to do

massive copy and paste on function names like you could get away with

changing code from Direct3D 10.0 to 11.0 In this situation you’ll most likely

Direct3D 11 Considerations 15

be better off creating a new rendering layer for your game and working off thestrengths of Direct3D 11 instead of trying to do a line-by-line search andreplace.

DirectX Tools

The DirectX SDK contains a wealth of information and tools for many related topics The SDK itself should be explored by all developers using DirectXbecause there are tremendously well documented and well developed tools thataid in the learning and/or developing of DirectX applications In this section wewill briefly take a look at some of the tools available in the DirectX SDK

DirectX-Sample Browser and Documentation

The DirectX SDK Sample Browser is a tool that displays all of the exampledemos, technical papers, tutorials, articles, and tools that come with the DirectXSDK The Sample Browser lists dozens of entries that include DirectX 11,DirectX 10, and DirectX 9 Whenever a new version of the SDK is released, it isrecommended that you check out the Sample Browser You might find theimplementation to a new technology or effect, a useful tutorial, or technicalinformation about everything DirectX

A screenshot of the Sample Browser can be seen in Figure 1.3 The samplebrowser can be found on the Start menu inside the subfolder for your DirectXSDK installation

Also of valuable use are the DirectX documentation and the Graphics umentation The graphics area of the SDK has its own documentation, which isimportant to know if you are looking for something graphics related and happen

doc-to open the wrong documentation file Also, Microsoft’s MSDN website has all

of this documentation and more available online

PIX

PIX is a tool used for the debugging and analysis of Direct3D applications asthey are executing PIX can give valuable information such as API calls, timingstatistics, and mesh information before and after transformation, to name a few.PIX can also be used for the debugging of shader code on the GPU, along withbreakpoints and the ability to step through code

Caps Viewer

The DirectX Caps Viewer shows information about the hardware’s capabilities

by way of detailing its support for Direct3D, DirectDraw, DirectSound, and

DirectInput Every piece of information about what the hardware supports and

its version are displayed by this tool A screenshot of the Caps Viewer can be

seen in Figure 1.4

Diagnostic Tools

The DirectX Diagnostic tool is used to test various components of DirectX to see

if they are working properly The diagnostic tool is used to create diagnostic

Figure 1.3

The DirectX SDK Sample Browser.

DirectX Tools 17

reports that can be saved to a file and/or sent to Microsoft Sending the report toMicrosoft is done via the Report button on the More Help tab of the tool If yoususpect some components are not working properly on a specific machine,running this tool can provide some insight.

texture formats supported by DirectX 9, not DirectX 10 or 11 If you are looking

to create images compressed with DXT1 through DXT5, this tool can do the job

N o t e

BC6 and BC7 are the new formats not supported by this tool The “BC” has replaced the “DXT” in

these compression formats.

The DirectX SDK also includes the Texture Converter The Texture Converter is

included with the TXVIEW.dll, which is installed as part of the DirectX SDK

installation The purpose of the Texture Converter is to convert an image from

one format to another The file formats that can be seen include:

The Texture Converter works by right-clicking on an image (or multiple images)

in the Windows Explorer and selecting Convert to File Format from the

drop-down list Once the dialog box appears, set the properties of the image you are

converting by setting its output size, format, and output filename, to name a few

You could also use the texture conversion command-line tool called TexConv

exe or TexConvEx.exe for Direct3D 10 and 11 textures The Texture Converter

extension was last compatible with DirectX 9

Error Lookup

The DirectX Error Lookup tool displays a description of any error code received

while running your DirectX applications You can enter the error code into this

application, hit the Lookup button, and it will describe the error to you Not all

DirectX Tools 19

errors are clear, and this tool can be useful The Error Lookup tool can be found

in the Utilities folder of your DirectX SDK installation

Control Panel

The DirectX Control Panel, located in the Utilities folder of the DirectX SDK, isused to examine and modify the properties of various DirectX components.With the Control Panel tool you can do the following:

n Enable the debug layer of Direct3D 10/11

n Change the debug output level and settings for use during development

n View driver information

n View version information for the various components

Cross-Platform Audio Creation Tool

The Cross-Platform Audio Creation tool is a GUI tool (also available with theDirectX SDK is a command-line alternative) for creating audio files used byXACT3, which is DirectX’s high-level audio API/component This tool is what

we’ll use to take our audio clip files and organize them into various banks, aprocess that is discussed in more detail in Appendix B (online)

A screenshot of the Cross-Platform Audio Creation tool can be seen in Figure 1.5.The XACT3 tool can be used to create audio files for Windows PC and the Xbox

360 For those doing game development using XNA, you can deploy a version ofthe audio files that matches the byte-ordering format of the processor within the

360 Since the Xbox 360 uses an architecture based on PowerPC, the same outputfiles for the PC cannot be used interchangeably with the Xbox 360 This will notaffect us in this book since this book assumes game development on an x86processor using DirectX 11 on Windows Vista or a Windows 7 PC

Game Definition File Editor

The Game Definition File Editor is used to create localized game definition filesfor Windows Vista and Windows 7 The information for a game definition file isdisplayed on the Games Explorer, which was discussed during the section titled

“The Components of DirectX 11.” A screenshot of the editor can be seen in

Figure 1.6

The Game Definition File Editor allows you to create properties for the game’s

release date, its Games Explorer icon and box art, its rating (e.g., Teen, Mature,

etc.), its name and description, and a host of other properties There is a detailed

tutorial of using the Game Definition File Editor that comes with the DirectX

SDK documentation You can also find this tutorial on the MSDN website by

searching for“Game Definition File Editor: Tool Tutorial.”

Down-Level Hardware

DirectX 11 supports a concept known as down-level hardware When DirectX

10 and Windows Vista were released, they were built for a new driver model and

hardware Although DirectX 11 is its own version, it has the ability to target the

Figure 1.5

The Cross-Platform Audio Creation tool.

DirectX Tools 21

DirectX 10.0 and 10.1 class of hardware with a single set of functions We’ll seethis in Chapter 2 when we build the first demos to check for compatibility withDirectX 11 first, and then for DirectX 10.1 and 10.0 if support for 11 isn’t there.Even if the application does choose DirectX 10.1 or 10.0, the same API callsapply, and as long as we are using Shader Model 4.0 and features not required byDirectX 11, the application will work just fine on that hardware If you do nothave DirectX 11.0 hardware it’s OK, since DirectX 10.0 hardware will work forall samples in this book.

Figure 1.6

The Game Definition File Editor.

As you go through the process of learning DirectX, don’t worry if things seem

overwhelming at times If this is your first time with video game graphics

programming, then DirectX, or OpenGL for that matter, will naturally have a

steep learning curve If you have experience with DirectX, you’ll find things are

much easier and much cleaner with Direct3D 10/11 If you are coming from

OpenGL, you’ll already have a handle on the more difficult and involved general

graphics programming concepts, and you can focus on learning the specifics of

the API itself

When learning DirectX, it is useful to pick a system and write as many samples

with it as you can The goal is to start small and work your way up By starting

small you allow yourself a realistic goal that you can build upon until you reach

your goal of DirectX mastery As you code demo by demo, before you know it

things start to make sense and fall into place If you ever get stuck, remember

you’re not alone; sites like UltimateGameProgramming.com, GameDev.net, and

Microsoft’s MSDN are great places to find help Like many things in life, the best

way to learn is to do it again and again until you’ve mastered the craft

Chapter Questions

Answers to all chapter review questions can be found in Appendix A on this

book’s companion website

2 Which is not a feature of DirectX 11?

A Fixed-function rendering pipeline

B Multithreaded GPU

C Offers HDR texture compression

D None of the above

3 Which version of DirectX does the Xbox 360 use?

A A modified version of DirectX 10

B A modified version of DirectX 11

Chapter Questions 23

C A modified version of DirectX 9

D A modified version of DirectX 8

4 DirectCompute was introduced in which version of DirectX?

A DirectX 11

B DirectX 10

C DirectX 9

D DirectX on the Xbox 360

5 DirectX 11 introduces which shader model?

A Shader Model 4.0

B Shader Model 4.1

C Shader Model 5.0

D None of the above

6 Which stage appears after the pixel shader?

A The geometry shader

B Output merger

C Hull and domain shaders (for tessellation)

D Vertex shader

7 The DirectX Control Panel is?

A There is no Control Panel in the DirectX SDK

B Used to install/uninstall DirectX

C An extension to the Windows 7 Control Panel

D Used to examine component properties

8 The Game Definition File is used for what purpose?

A To edit the game’s resources, such as images and models

B To create a game’s help manual

C To create a game installer

D For creating localization files for the Games Explorer

9 PIX is what type of tool within the DirectX SDK?

A Used for performance analysis

B Used for texture viewing

C Used for texture converting

D None of the above

10 How many stages did we discuss for Direct3D 11?

A 12

B 7

C 9

D 11

11 Geometry shaders are used for tessellation (true or false).

A True

B False

12 The geometry shader stage occurs before the vertex stage and after the

pixel stage (true or false)

15 Compute shaders is a new shader type in DirectX 11 for general-purpose

computing (true or false)

A True

B False

Chapter Questions 25

Your First DirectX

Program

The best way to begin learning DirectX is to start at the beginning by creatingsimple demo applications In this chapter we’ll take you step-by-step through theprocess of creating your very first DirectX application, specifically focusing onDirect3D By the end of this chapter you will have a firm understanding of thesetup of Direct3D from start to finish

In this chapter:

n How to create a project

n How to initialize DirectX

n How to clear the screen

n How to display a scene

Creating the Project

This book assumes you’ve already had experience creating C++ projects andworking within Visual Studio In this section and the one to follow we’ll brieflycover the initial setup of a Win32 application We’ll modify this code throughoutthe chapter to include Direct3D initialization and basic rendering By the end ofthe chapter we’ll have a set of code used to create and initialize Direct3D that wecan use for all demos throughout this book

Chapter 2

27